1. Field of the Invention
Aspects of the present invention relate to an input signal level detection apparatus and method, and more particularly, to an apparatus and method for detecting a level corresponding to an effective value of an input signal.
2. Description of the Related Art
An effective value, also called a root mean square value (RMS), is used to represent a magnitude of an analog signal. Detecting a level corresponding to an effective value of an input signal includes detecting a mean amplitude of an input signal such as an analog signal.
A conventional analog signal level detection apparatus includes a rectifier and a plurality of operational amplifiers. Each operational amplifier, however, has an offset that changes according to a layout and a manufacturing process. For example, in a complementary metal oxide semiconductor (CMOS) process, an operational amplifier normally has an offset ranging from a few mV to tens of mV and, in some cases, has an offset ranging from 100 mV to 200 mV. Therefore, as the analog signal level detection apparatus uses more operational amplifiers, the detected level may be greatly deviated by the offset, leading to the degradation of detection accuracy. Furthermore, power consumption of the analog signal level detection apparatus may be increased.